c     file name: asdd.for

      subroutine asdd (ak, gmdd, bsagx0)

c     + + + PURPOSE + + +
c agg size distribution eq. S(68), and S(69)
c (aggregation process) due to wet/dry

c     + + + AUTHOR + + +
c     Imam Elminyawi

c     + + + KEY WORDS + + +
c     wind erosion, soil processes, ....

c     + + + ARGUMENT DECLARATIONS + + +
      real ak, gmdd, bsagx0

c     + + + LOCAL VARIABLES + + +
      real anc
      real xx

c     + + + LOCAL DEFINITIONS + + +
c     anc

c     + + + END SPECIFICATIONS + + +

      anc = 0.0

      if ( gmdd .ge. bsagx0 ) go to 100
c This should not be negative.....................
		 if (ak .lt. 0) then
			ak = 0.1
         endif
         anc = - ak * alog( 1.0 - gmdd / bsagx0 ) + 1.0
c         anc = (-1/ak) * alog( 1.0 - gmdd / bsagx0 )
c        gmdd = bsagx0 * ( 1.0 - exp(- anc / ak) )
         gmdd = bsagx0 * ( 1.0 - exp(- xx) )
 100  continue

      return
      end